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Metabolic control and growth during exclusive growth hormone treatment in X-linked hypophosphatemic rickets

Outi Makitie1, Sanna Toiviainen-Salo, Eino Marttinen

  • 1Hospital for Children and Adolescents, Pediatric Endocrinology and Metabolic Bone Clinic, Helsinki University Hospital, Helsinki, Finland. outi.makitie@helsinki.fi

Hormone Research
|January 22, 2008
PubMed

Insights

Growth hormone (GH) therapy improved phosphate levels and height in children with X-linked hypophosphatemic rickets (XLH). However, GH treatment may worsen existing bone deformities in some patients.

Area of Science:

  • Pediatric Endocrinology
  • Metabolic Bone Diseases
  • Growth Hormone Therapy

Background:

  • X-linked hypophosphatemic rickets (XLH) is a rare genetic disorder affecting phosphate metabolism and bone health.
  • Growth hormone (GH) is explored for its potential to improve phosphate balance and linear growth in XLH patients.

Purpose of the Study:

  • To evaluate the efficacy of exclusive recombinant human GH (rhGH) therapy on phosphate homeostasis and growth in children with XLH.
  • To assess the impact of rhGH on biochemical markers and skeletal parameters in XLH.

Main Methods:

  • A 12-month trial involving ten children with XLH (median age 12.2 years) receiving rhGH (0.033 mg/kg/day).
  • Conventional treatments were paused before GH initiation; 1alpha-hydroxyvitamin D and oral phosphate were added sequentially.
  • Patients underwent regular clinical, biochemical, and radiographic assessments throughout the study period.

Main Results:

  • Serum phosphate Z-scores significantly increased at 6 and 9 months, returning to baseline by 12 months.
  • Significant increases in serum 1,25-dihydroxyvitamin D and normalization of parathyroid function were observed.
  • Median height Z-score improved from -2.2 to -1.7; however, one patient showed increased rickets activity and three experienced worsened lower limb deformities.

Conclusions:

  • rhGH therapy effectively improves phosphate levels, vitamin D metabolism, and longitudinal growth in XLH.
  • While beneficial for growth, rhGH may pose a risk of exacerbating pre-existing skeletal deformities in XLH patients.
Abstract

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